The board file is much easier than the chip file. It basically involves loading the chip file and just mapping the chip pins to the physical pins on the board. At this time there hasn't a consistent naming of the pins due to the documentation provided by different manufacturers referencing the pins by different names.
For instance, naming pins like D4, to imply it is a digital pin number 4, or GPIO22 are pretty common. Some boards also use the same name as the microcontroller pin name like PC0. However, if the board you are using has a Raspberry Pi style connector, we recommended that you go with the D naming scheme since using a name like D4 will make it so it is more consistent with existing CircuitPython examples without needing changes.
If you followed the instruction in the software setup, you should have the Adafruit_Blinka folder in your home directory. Inside of there you'll want to navigate to src/adafruit_blinka/board which is where all of the board files are located, some of them sorted by manufacturer.
For the Pine64, I'm just going to create a file called pine64.py. The first step is to start with creating each of the D pins and assigning it to the pins defined in the chip file. Once that's done, the next step is to create any aliases that are needed such as pins for I2C. We'll go over those a bit more in depth later in this guide. Here are the contents of the board file for the Pine64:
# SPDX-FileCopyrightText: 2021 Melissa LeBlanc-Williams for Adafruit Industries # # SPDX-License-Identifier: MIT """Pin definitions for the Pine64.""" from adafruit_blinka.microcontroller.allwinner.a64 import pin D2 = pin.PH3 D3 = pin.PH2 D4 = pin.PL10 D5 = pin.PH5 D6 = pin.PH6 D7 = pin.PH7 D8 = pin.PC3 D9 = pin.PC1 D10 = pin.PC0 D11 = pin.PC2 D12 = pin.PC4 D13 = pin.PC5 D14 = pin.PB0 D15 = pin.PB1 D16 = pin.PC6 D17 = pin.PC7 D18 = pin.PC8 D19 = pin.PC9 D20 = pin.PC10 D21 = pin.PC11 D22 = pin.PC12 D23 = pin.PC13 D24 = pin.PC14 D25 = pin.PC15 D26 = pin.PC16 D27 = pin.PH9 SDA = D2 SCL = D3 SCL2 = pin.PL8 SDA2 = pin.PL9 SCLK = D11 MOSI = D10 MISO = D9 CS = D8 SCK = SCLK UART_TX = D14 UART_RX = D15 UART3_TX = pin.PD0 UART3_RX = pin.PD1 UART4_TX = pin.PD2 UART4_RX = pin.PD3
